Here's one that I saw last year.

In a Federation game, runner is on first, 1st baseman in front of the baseline.

A shallow pop up is hit behind first base, and in foul territory. The 1st baseman spins, collides with the runner, and chases the pop up.

The pop up is just barely out of reach, and clearly could have been caught if no collision had occured.

Interference or incidental contact?

-JN

I believe it to be interference.
The intent of the runner does not come into play and we should also not try to determine if there was an impact on the play i.e. if the defensive player is impeded then "interference" must be called.

Unless the runner is still standing on tthe base he/she has an obligation to avoid the fielder.

If the runer is not on the base I would call interference.

Let's take it 1 step further. Say No Outs.
You call it interference.
Who is out ?
Does it matter if the interference is Intentional or not ??